The same mineral can form in many different colors. There are thousands of different minerals, and they can be difficult to identify solely by their appearance. For example, quartz (SiO2) can come in a wide range of colors, including white, purple, orange, and even black. A variety of quartz called "smoky quartz" can be viewed in the image shown here. If color is an unreliable indicator, how does a geologist know how to classify a mineral? Geologists use a variety of physical tests to examine and classify minerals. In this topic, you will explore the testing and identification of minerals based on their physical properties.
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